Should the Basin Reserve flyover be an iconic structure that defines the capital city or a modest bridge that quietly slinks into its surrounds?

That question has dominated the flyover's board of inquiry hearing today as the New Zealand Transport Agency and opposition groups debate the $90 million project's design.

The agency is seeking resource consent to build a two-lane highway flyover 20 metres north of the Basin Reserve, linking the Mt Victoria Tunnel to Buckle St.

Urban designer Yvonne Weeber, acting for opponents Save the Basin, told the board this morning that the flyover would be a blight on the landscape that is impossible to hide.

The agency has said it will build a pavilion at the Basin's northern entrance and a "green screen" of vines outside Grandstand Apartments to shield the flyover from view.

It also opted for what it called "a simple yet elegant" flyover design, rather than an iconic feature bridge, so the structure would not overshadow surrounding heritage buildings, such as the National War Memorial.

In documents presented to the board, Weeber said the agency's proposed design would not create any visual interest.

The shape of the pillars was out of sorts with the shape of the main structure and balustrade, leading to an "incoherent" structure.

Her preference was for no flyover at all. But if one had to be built, then it should be a more iconic design, she said.

"If you have to have a bridge then it should be the best possible bridge you can design because of where it's placed, and this [proposed design] is not the best possible bridge."

Screens should also be built on the flyover rather than having a pavilion that would block views of the "void" between the Basin and Kent and Cambridge Tce, she said.

Agency lawyer Andrew Cameron grilled Weeber on that point, given she had also criticised the agency's proposed design as being too bulky.

Putting screens on the flyover would only add to its bulk, he said. "Do you accept that your evidence on this point is wholly inconsistent?"

Weeber said temporary screens were an option, so that the bulk was only noticeable when cricket was being played.

Cameron said that, from a player and spectator perspective, that was unacceptable because it would make the flyover more obvious.

Weeber agreed, but said it depended on how "elegantly" the temporary screens were designed.

Cameron said that if the pavilion was only 45m in length, rather than the maximum 65m, then people would still be able to see the void. Weeber did not share his view.

"You've got a large bulky bridge in the way. I'm sure that's what people will see ... there's only a sliver of light [underneath]," she said.